Spontaneous Rupture of Mature Teratoma at the Cerebellar Vermis Comorbid With Dermal Sinus Tract and Subcutaneous Lipoma

Intracranial teratoma, a subtype of non-germinomatous germ cell tumors, is rare in adults. Clinical presentation of intracranial teratomas varies according to where they grow. In particular, cases of spontaneous ruptures of intracranial teratoma are sporadic. This study reports the case of an adult with a spontaneously ruptured mature teratoma in the cerebellar vermis, which was comorbid with a dermal sinus tract and subcutaneous lipoma. Before surgery, because the images were atypical of a teratoma, the patient was misdiagnosed as having vascular malformation rupture and bleeding in the cerebellar vermis. Due to the patient's level of consciousness dropping drastically to a coma, a craniotomy was performed. During the surgery, the tumor was observed to be a mixed cystic and solid mass. The liquid in the cyst was dark green and with a fatty component. The solid part had a tough texture and comprised hair, fat, cartilage, and calcification components. Post-surgery multipoint biopsy proved that it was a mature teratoma and that it was connected to a subcutaneous lipoma through the dermal sinus tract across the occipital bone. After proactive treatment, the patient's prognosis was favorable.